This proposal is designed to investigate hormone receptors in individual breast cancers; to define the chemical and immunological properties of cell membrane receptors; and to relate this information to properties of derived cell lines in tissue culture. The endocrine component will emphasize the ontogeny of hormone receptors in mammary gland and their concentration, specificity, inducibility and clinical applicability in breast cancer and other surgical breast specimens. The chemical studies will concentrate on the properties of normal and neoplastic mammary cell membranes with the hope of purifying distinct tumor components for assessment of their potential as tumor markers. Tissue culture will be done employing techniques which we have found successful for the growth of endothelial cells and other neoplasms. Assessment of the presence and chemical characteristics of receptors in cultured cells, their inducibility, relation to cell growth, differentiation and susceptibility to chemotherapeutic substances will proceed from success in this area. Our goal is to advance knowledge about breast cancer and implement new information into the clinical sphere by relating receptor information to the clinical presentation, epidemiologic history and management of the individual patient.